The present invention relates to a structure of an ion exchange membrane employed for such an electrochemical cell as a fuel cell.
Heretofore, the bonding between the ion exchange membrane and the electrodes of a fuel cell has been thermally conducted by means of pressing or rolling under pressure (U.S. Pat. Nos. 3,134,697, 3,297,484 and 3,432,355).
When the bonding temperature is lower than the glass transition temperature of the ion exchange membrane, the sufficient bonding strength cannot be obtained. On the other hand, when the temperature is higher than the glass transition temperature, the sufficient bonding strength can be obtained, but the ion exchange membrane frequently encroaches into the electrode too deeply under wet conditions so that it may increase active carbon area.